Drive lug for pilot bit and earth boring augers



Jan. 27, 1959 G. A. M. PETERSEN 2, 70,

- DRIVE LUG FOR PILOT BIT AND EARTH BORING AUGERS Fi led Nov. 15, 1954 2Sheets-Sheet 1 INVENTOR. GERALD AM PETERSEN AT TORNEYS Jan. 27, 1959 G.A. M. PETERSEN 2,

DRIVE LUG FOR PILOT BIT AND EARTH BORING AUGERS Filed Nov. 15, 1954 2Sheets-Sheet 2 INVENTOR. GERALD/4M PETERSEN A T TORNEYS United StatesPatent DRIVE LUG FOR PILOT BIT AND EARTH BORING AUGERS 9 Claims. (Cl.255---61) This invention relates to earth boring tools or angers andmore particularly to drive lugs for that portion of the tool whichencounters the earth first, commonly referred to as a pilot bit.

The present invention relates to certain novel improvementsin the drivelug or coupling of the pilot bit to a drive or auger shaft in the manneras generally shown in my co-pending application Serial No. 414,007,filed March 4, 1954, now Patent No. 2,773,673, in the United StatesPatent Oflice.

It is an object of this invention to provide a simple drive lug foradapting a drive shaft'to receive a pilot bit.

Another object is to provide a drive lug so constructed as toeffectively absorb the reacting forces to which it i is subjected Whilein driving relation with a pilot bit.

Another object is to provide means for coupling a pilot bit to a driveshaft or anger in a manner to provide continuous upward flow of spoil.In this connection it is a further object to provide a coupling mediawith a passage system communicating a fluid carrying bore in a driveshaft with discharge ports in the region of boring of the pilot bit. i

Yet another object is to provide a coupling means in the form of a drivelug conforming with the contour of a pilot bit body in a manner togenerate a maximum of driving energy between a drive lug and pilot bitwith a minimum of weakening of the assembly so constructed. In thisconnection it is an object to provide a drive lug having a diametricallyextending key portion flanked by partial ear portions in a leadingdirection with respect "ice Fig. 7 is an enlarged elevation similar tothat of Fig. 4 partly broken away to illustrate the communication offluid passages through the several parts thereof.

Fig. 8 is a fragmentary elevationtaken from the same angle as that ofFig. 4, also illustrating the communication of fluid passages.

Fig. 9 is a horizontal section through Fig. 7 taken substantially alongline 9-9 thereof.

Fig. 10 is a perspective view of a modified form of the drive lug shownin either Figs. 1 through 5 or 6 through 9.

Fig. 11 is a section through Fig. 10 taken at line 11 thereof.

The coupling means 10 of the present invention consists of a drive lug11 for connecting a pilot bit 12 to a drive shaft 13. For purposes ofclarity and inorder to distinguish between the different forms of thedrive lug and associated parts, whole numbers, such as 10, 11, 12 and13, will be used in explaining Figs. 1 through 5,as Well as Figs. 10 and11, while similar numerals with prime exponents will designate likeparts in Figs. 6 through 9. i I At the outset it should be understoodthat the coupling means 10or 10' embodying the present inventioncontemplates the use of a pilot bit 12 or 12 having a central bodyportion 14 or 14' of sufficient girth to accommodate the drive lug 11 or11'. For example, the main body or central core of the pilot bit shouldbe enlarged at its base or upper end, and gradually taper toward itsopposite end, or, be preferably of cone shape as illustrated and as moreparticularly described and claimed in my aforementioned co-pending' U.S. application, Serial No. 414,007.

to the direction of turning of the drive lug. The object 3 of thisconstruction is to effect a minimum of counterforces on, the leading ordriving faces of the key and ear portions of the drive lug so as toobtain a maximum of dynamic efficiency.

These and other objects and advantages of the present invention willbecome more apparent from a reading of the following description whentaken in the light of the drawings in which:

Fig. 1 is an elevation of a drive lug secured to a drive shaft inaccordance with the present invention.

Fig. 2 is an enlarged top plan view of apilot bit adapted for receipt ofthe drive lug of Fig. 1.

Fig. 3 is a bottom plan view of the drive lug of Fig. 1 andcomplementary to, and adapted to be received in the pilot bit ofFig. 2.

i Fig. 4 is an enlarged elevational view of the drive log in Fig. 1 andthe pilot bit in Fig. 2 assembled and partly broken away for purposes ofillustration.

With the foregoing in mind, the coupling means of the present inventioncontemplates the provision of a socket 20 or 20 in the enlarged or upperend of the body portion 14 or 14 or'more strictly speaking, the base ofthe cone shaped body thereof. This socket 20 or 20 is formed toaccommodate the drive lug 1-1 or 11 and therefore the drive lug will beexplained first.

Referring tov Figs. 1, 3, 4 and 5, the lug 11 is a keylike fittinghaving a plate-like formation 21 on. its upper face formed integrallywith alower key portion 22. This plate-like formation is preferablyconfined to a shape within the mean diameter of the base of the coneshaped body 14 of the pilot bit 121 as well as that of the drill shaft13. Thus the joint between these three elements, namely the pilot bit,the lug and the drive shaft, is relatively straight and uniform with noprojections therefrom.

The key portion 22 of the lug 11 as best seen in Figs. 3 and 5 isadapted to be coaxially disposed with respect to pilot bit and driveshaft. To this end the key portion 22 of the lug is symmetrical in planas illustrated in Fig. 5, and relative to the axis A about which thedrive lug turns. In plan, the key portion extends substantiallydiametrically across the mean diameter of the plate-like formation 21 atthe upper end of the lug. In accordance with the present invention, thediametrical key portion 22 is providedwith a twist in the direction ofrotation of the pilot bit for reasons more particularly explained laterin connection with the pilot bit. The lug 22 also includes a pairoflateral cars 23 and 24 on either side of the diametrical key but in aleading direction thereon relative to a line transverse to thediametrical key 22, and in relation to the direction of rotationthereof. These ears 2-3, 24 are formed integrally with the key portion22 as well as the upper disc portion 21 as will be clearly seen in Figs.1, 3, 4 and 7. The ears 23, 24 extend downwardly only partly the depthof the key portion 22, the extent of the depth of the ears being limitedonly by the girth of the central body portion '14 or 14 of the pilotbit. In other words, the limitation occasioned by the ability of thecentral body of the .pilot bit to ,provide for the socket 20 to receiveboth cars 23., 24-as well as the diametrical key portion 22. p

'The lower extremityof the key portion 22 is provided with an eyeportion 25, a relatively U-Shaped appendage 26 having its legs 27 and 28formed integrally with and depending. from the lower edge of the keyportion 22. This leaves an opening 29 in the eye portion for thereceiptof a bolt or pin 30 for securing the pilot bit to the drive lug11.

Referring now more particularly to the pilot bit '12 or 12", the form ofwhich may be any desired design provided it has a central body portion14 or 14 suitable for the receipt of the drive lug 11 or 11' in a mannernow to be explained. The pilot bit 12 or 12 has diametrically opposedspiral blades 31 and 32 which extend radially .(i-n plan section) fromthe cone-like central body portion 14 or 14" as the case may be. It isalong a diame'tricaliline extendingfrom blade to blade that the socket'26 .is formed to receive the diametrical key portion 22. Thisis clearlyillustrated in Figs. 2 and wherein it will be noted that the extremitiesof the key portion 22 extend partially into the body of the blades attheir zone of joinder with central body portion 14 'or 14. Since eachblade 31, 32 is formed concave on its leading face and convex on itstrailing face, the substantially diametric socket 20 has a slight twistconforming to the contour of a transverse section through the blades.This assures sufficient body between the walls of the socket and theexterior surface of the pilot bit as is well illustrated in Fig. 5. Inaddition to the foregoing, and as depicted in Fig. '2, a partial recessor well 33, 34 is provided adjacent the socket 20 to accommodate theears 23, 24, respectively, which extend from either side of the keyportion 22 of the lug.

The socket 20 extends downwardly into the main or central body of thepilot bit sufficiently to receive the key portion 22 of the lug 11. Atthis zone of the main body 14 or 141, the latters taper or conical shapelimits the depth of the socket at the full width of the key 22. Thus atthis zone the socket narrows down to a recess 35 'confi'guiated toreceive the eye portion 25 as best seen in Figs. 4 and 8. Moreover,since the eye portions 25 and 25 are narrower than the key portion 22 ofthe drive lug (Figs. 3 and 7) each recess 35 and 35 can also be narroweddown in a'direction transverse to the diametri'cal key :22 as best seenin Figs. 2 and 7, respectively. For this reason the cone like body 14 or14 can be recessed somewhat from the outer sides to provide verticalwalls 36 and 37' on either side of the eye por tion 25' as is clearlyillustrated in Fig. 7 only. It is at this plane or zone that thecone-like body is provided with a bore 38 for the receipt of the pin orbolt 30 by which the drive lug is secured to the pilot bit.

Referring now to Figs. 2, 5 and 6, it should be understood that thepilot bit 12 or 12 is to be driven in a clockwise direction about axis Aas depicted in these views. As previously explained in connection withthe drive lug it will be remembered that the latter is provided withears 23, 24 which are in a leading direction relative to the directionof rotation thereof. The theory of this construction is diagrammaticallyillustrated by the force arrows f within the socket 26 as depicted inFig. 5, wherein the entire assembly turns about the axis'A in thedirection of arcuate arrow n. Force arrows f illustrate the leadingfaces of the two ends of the key portion 22 hearing against the adjacentcomplementary walls of the socket 2%. Force arrows f illustrate theleading faces of the two cars .23, 24 hearing against the adjacentcomplesrnentary walls -of the side wells 33, 34. With the cars 23 and 24on opposite sides of the diametrically extending key 22 a forward thrustin the direction of arrows f on these ears supplements the thrust in thedirection of arrows f at the extremities of the key 22. Since the totalforce required to turn the pilot bit is divided between the extremitiesof the key 22 and the two side cars it will be appreciated that theamount of force required at the extremities of the diametricallyextending key is appreciably lessened. In other words the total force isdistributed between the leading faces of all four major projections onthe drive lug. Consequently it may be said that the amount of forcerequired at the extremities of the diametrically extending key portionis appreciably less 'thanit would be if the two'ears '23 and 24 were notemployed. To .put it another way, the two ears 23 and 24 in effectminimize the counterforces or resistance to the forces at say arrows fon the leading faces at the two ends of the diametrically extending keyportion 22.

In addition to the foregoing, since the ears 23, '24 are each disposedin advance of a line transverse tothe diametrically extending key 22they each exert a force directly behind the respective extremities(driving ends) of the key 22. Moreover, the key 22 is materiallyreinforced at a critical zone, i. e., directly behindeach forwardlymoving half of the diametrically extending key.

:As seen in Fig. 5, the forces f exerted by the leading faces of theextremities of the key 22 are transmitted toward thelcading faces of therespective blades 31 and 32. It will also he noted that the forces f oneach car 23, 24. are directed against the heel end of each blade 31, 32exerting a driving force axially outward thereof.

The foregoing theory of drive connection is equally true with respect tothe form of drive connection between the lug 11 and .pilot bit l2 shownin Figs. 6 through 9. The only difference between the form in Figs. 1through 5 and the form in Figs. 6 through 9 resides in the provision ofa system of passages P in the latter form for the admission of air,fluid or other such clearing media to the bore being :made by the pilotbit 12.

In connection with the foregoing, it will be seen (Fig. 7) that thedrill shaft 13 is provided with a central bore B communicable at itsupper end with a source of fluid supply (not shown) This may beaccomplished in any usual or well known manner by a hydraulic pump 'orcompressed air apparatus whichever is desired. it is contemplated thatthe fluid supplied via the bore -B shall be distributed equally toeither side of the pilot bit, i. e., to a zone to the rear of each blade31', 32 thereon for distribution into the zone of cutting of the leading'end of each blade at the tip of the pilot bit. To this end the pilotbit 12' is provided with exit ports 4% and 41 each communicating withthe lowermost extremity of the socket 20', i. e., the recess 35 thereofas depicted in Figs. 7, 8 and 9. It will thus be appreciated that thesocket 20 itself becomes a part of the passage system P by which thefluid is conveyed. This is so because as noted in Fig. 5 there is aclearance space between the trailing face of each key portion 22 and thewall :of the recess 20 behind it. There is also a clearance space -between the trailing face of each of the ears 2324 and the wall of therespective recess 33 and 34 behind them. These clearances are alsoprovided in the unit of Figs. 6, 7 and 8 although the parts aredesignated with prime numerals 20', 22', 23', 24, 33 and 34',respectively. In addition to theforegoing, it will be noted in Fig. 8

i that the recess 35 is flared outwardly at its upper open end to mergewith the end walls of the diametrical recess 20'. Moreover as seen inFig. 7 part of the central body 14 of the pilot bit is removed to therear of the side wells 33', 34 where the cars 23', 24 seat. The removalof such portion of the central body portion in a zone where little or nobearing occurs between the drive lug and-the pilot bit does not weakenthe latter and serves to com Plate the passage 'system P toa point to:the rear-jo'f each of the ears 23'. 24 on the lug 11. Here theilugfill' is provided with exit ports 43, 44 at the terminal ends of said keyportion and the cone shaped central body of said bifurcated passages 45,46 which converge with the bore 1 B in the drive shaft 13.

Since the provision of bifurcated passages, such as the ones 45 and 46above explained, would not ordinarily occur in a common bored driveshaft, it is proposed that the drive ing 11' be welded to a speciallybuilt length or stud of shafting 47' preformed in the manner described.Theupper end of the stud 47' could be welded in alignment with the drillshaft 13 or, as illustrated in Fig. 7 can be secured to the latter bythreaded connection.

So far as concerns the mode of connecting the drive lug to any form ofdrill shaft, a short cap such as the one 47 shown in Fig. 1 may beemployed. In this form the upper plate-like formation 21 of the lug iswelded to the bottom of thecap 47. It should be apparent that the discformation 21 may also be connected directly to the drill shaft 13 as bywelding in the manner illustrated in Fig. 4.

Referring now to the lug illustrated in Figs. and 11, the same may beconstructed as explained in connection with either Figs. 1 through 5 orFigs. 6 through 9. The

main distinction in the lug of Figs. 10 and 11 resides in the provisionof a lateral or radial extension 50 on the plate-like formation 21thereof to fill upthe gap between the lower end of the helical blade Hon the drill shaft (or auger) and the upper end of one of the blades 31or32 on the pilot bit 12 or 12.

Thus it will be seen in Figs. 10 and 11 that the upper disc formation ofeither form of drive lug 11 or 11' when provided with the lateral arm 50may be welded directly to the lower end of an anger shaft, the arm -50-being simultaneously welded to the lower terminal end of the helicalblade H thereof. Now then the auger thus supplied with the lug isadapted to be coupled to a pilot bit in the same manner as describedabove with assurance that at least one of the blades 31 or 32 of thepilot bit will be in register with the helical blade H of the auger. Ofcourse it will be understood that should the auger be provided withdouble helix blades each of the latter may be secured to lateral arms50, the lug being provided with two such arms. In this case both blades31 and 32 of the pilot bit will be registered (by the key-like lug) withthe double helix blades of the auger.

While I have illustrated and described a preferred embodiment of thepresent invention, it will be understood however, that various changesand modifications may be made in the details thereof without departingfrom the spirit and scope of the invention as set forth in the appendedclaims.

pilot bit for attaching the latter to said drive lug.

2. In combination with a pilot bit of the type having dual helicalblades formed integrally with a relatively cone-shaped central bodyportion, means for coupling said pilot bit to a drive shaft comprisinga. drive lug having a plate-like formation secured to the end of saiddrive shaft, said drive lug comprising a depending diameplementary to,said key portion for receiving the same,

Having thus described the invention, What I claim as new and desire toprotect by Letters Patent is defined in the following claims.

I claim:

1. In combination with a pilot bit of the type having dual helicalblades formed integrally with a relatively cone-shaped central bodyportion, means for coupling posed perpendicular to said key portion oneither side thereof, said key portion spanning the full diameter of saidplate-like formation between the dual blades of said pilot bit andtwisting congruent to the helical trend thereof to a depth limited bythe abilityof the cone-shaped central body of said pilot bit to receivethe same, said cone shaped central body having a socket formed thereincomplementary to said diametrically extending key portion for receivingthe same, said ears between said plate formation and key portion eachbeing disposed in a leading direction relative to the direction ofturning of said drive shaft for transmitting direct driving forces tosaid pilot bit and for minimizing counterforces of the latter againstsaid key portion, and a bolt extending through said socket extendingdiametricallybetween the dual helical blades of said pilot bit andtending in a helical twist congruent to the helix of said blades, saidkey portion being twisted in conformity with the helical twist in saidsocket, and an ear formed between said plate formation and key portionon each side of the latter, each said car being disposedin a leadingdirection relative to a line transverse to said key portion and inrelation to the direction'of turning of said drive shaft fortransmitting direct driving forces to said pilot bit and for minimizingcounterforces of the latter against said key portion, and a boltextending through said key portion and the cone-shaped central body ofsaid pilot bitfor attaching the latter to said drive lug.

l 3. Coupling means between a drive shaft and a pilot bitcoinprising adrive lug having its upper end secured to the lower end of said driveshaft, a diametrically extending key portion formed integrally with theupper end of said drive lug and depending therefrom, an ear formed oneither side of said key portion and each disposed in a leading directionrelative to a line transverse to the diametrically extending key portionand with respect to thedirectio n of turning of said drive shaft, saidpilot bit having a solid central body portion the upper end of whichconforms substantially to the upper end of said drive lug for abuttingrelation therewith and provided with a diametrical socket complementaryto said key portion for receiving the same, a shelf-like recess formedin the central body portion of said pilot bit on either side of thesocket therein complementary to said ears forreceiving said'ears, and abolt extending through said pilot bit and said key portion for securingsaid pilot bit to said drive lug.

4. Coupling means between a drive shaft and a pilot bit comprising adrive lug having a plate-like formation confined within the diameter ofthe lower end of said drive shaft, means for securing the plate-likeformation said pilot bit to a drive shaft comprising a drive lug havinga a plate-like formation secured to the end of said drive of saidlug tothe lower end of said drive shaft, a diametrically extending key portionformed integrally with said plate-like formation and dependingtherefrom, an ear formed on each side of said key portion and integrallywith said plate-like formation, each said ear being disposed in aleading direction with respect to a line transverse to said diametrickey and relative to the direction of turning of said drive shaft, saidpilot bit having a solid central body portion the upper end of whichconforms substantially to the plate-like formation of said lug forabutting relation therewith, the central body portion of said pilot bitbeing provided with a diametrical socket complementary to said keyportion for receiving the same, a pair of shelf-like recesses formed insaid central body portion, one on either side of said socket inconformity with the disposition of the ears on said lug for receiving"said pair of ears, said key portion having an eye formed therethroughtransversely thereof, said solid central body portion of the pilot bithaving aligned bores formed therethrough in register with the eye formedthrough said key portion, and a bolt extending through said alignedbores and the eye formed in saidkey portion for securing said pilot bitto said drive lug 5. Coupling means between a 'helically bladed augershaft andapilot-bithaving 'a'helical bladecomprisiug a drive lug fhaving.a vplate-like formation secured to the *lowerr endiof' saidaugershaft,'-a key portion formed inteigrally'with andldiarnetrically acrosssaidplate-like fornration anddepending therefrom, an ear'formedon eachside of said key portion, each said ear being disposed in a leadingdirection with respect to :a li-ne transverse to said key:portion andinthe direction of turning-of said auger shaft,-said pilot bit having asolid central .fbody portion the upper end of which conformssubstantially to the plate-like formation of said lug for :a'buttingrelation therewith, the central body portion of said pilot bit beingprovided with a diametrical socket complementary to said key: portionfor receiving the same a pair ofi'shelf ilike recesses formed'in thecentral bodytportion of said-pilot bit on either side of said-socketcomplementary to said ears forireceivingsaid pairofears, apin extendingthrough said pilot bit and said keyrportion for securing said pilotbittosaid drive lug, and alateral arm formed integrally with theplate-like formation of 'saidlug in a position'to registerwith thehelical blade of said auger and thehelical blade of said pilot bit.

6. In a'coupling means between -a bored drive shaft and a pilot bithavinghelical blades provided :with passages exiting on the trailingside of each of saidhelical 'blades, a drive lug having aplate-likeformation secured tothe lower end of said drive shaft and provided withdiverging passages converging at the plane of registerwith the bores insaid drive shaft, a keyportion formed integrally "with said plate-likeformation and depending therefrom .diametrically thereof, a pair ofearsformed integrally with saidplate-like formation and said key portionso as-to extend laterally from each side of said key'portion'in aleading direction relative to a line transverse to said diametricallyextending key portion with respect-to the di- 'rection of turningof saiddrive shaft and ahead'of the outlets of the diverging passages in saidplate-like formation, said pilot bit having a solid central bodyport-ion the upper end of which conforms substantiallyto said "platelikeformation for abutting relation therewith, the central body of saidpilot bit being provided with a diametrically disposed socket toreceivesaid key portion and having a pair of shelf-like recesses on either sideof said socket complementary to the ears on either sideof saidkey'portion for receiving the ears, said keyportion and saidears leavinga clearance space between their trailing faces and the respectiveadjacent wall of said socket and recesses behind them for communicatingtheoutlets of the diverging passages in said plate-like formation withthe base of said socket, the base of said socket having communicationwith the passages exiting on the trailing side of each of said helicalblades, and a bolt extending through said pilot bit and said key portionfor attaching said pilot bit to said drive lug.

7. in combination with a pilotbit ofthe type having diametric helicalblades formed integrally with a relatively cone-shaped central bodyportion, -means for coupling said pilot bit to a drive shaftcomprisingadrive lug'having a plate-like formation secured to the end of saiddrive shaft, said drive'lughaving a depending key portion formedintegrally with said plate-like formation and extending the fulldiameter of the same and tea depth limited by the ability of saidcone-shaped central body of saidtpilot bit to receive the same,saidconewshaped central body having a socket formed therein complementary tosaid key portion for receiving the same and having a pair of shelf-likerecesses formed insaid central bodyrone on either side of said socketand each in advance of-ai-line transverse to saidsocket andinrelation-to the direction of turning ofsaid pilot bit,a pair of earsformedintegrally with and between said plate-likeformationaand'keytportion, each:saidearbeing-disposed in a leadingdirec'tion one'ithe'r isideafof said key portion andrelative :to' thedi'rection of'turning of said drive shaftforitransmittingdirectu'drivinlg forces from said drive=lug IOSQld PllGlZbII and forminimizing counterforces-of -'the latter against said skey .portiomanda'bolt extending through saidsnkey portion :and the cone-shaped central'bodyof said :pilot bit for attaching the latter to said drive lug.

'8. In combination with :a pilot bit of the'typeihaving dual thelicalblades formed integrally with a relatively .iconeshaped central bodyportion, means for couplingsaid pilotbit to a drive shaft-comprisingadrivelugzhavinga plate-like-forrn'ation securedito the end ofsaiddriveshaft,

said drive lug comprising a dependingidiametricallkeytportion formedintegrally with said 'plate like formation and flanked :at each of itssides by antear portion, said conesliap'ed central body having a socketformed therein complementary to said key and earportionsfor receivingtheandaa bolt extending through said 'alignedboresandthe eye formed 1insaid key portion for-securing said pilot bit tto'said .drive lug.

9. The combination with a pilot bit of the type having diametric helicalblades formed integrally with a relatively cone-shaped centralbody-portion and a drive shaft having an axial bore, ofmeans forcoupling said-'p'ilot bitltoxsaiddrive shaft comprising a drive lughaving 'a plate-like formation secured to the end of said -drive :shaft,:said'drive lug comprising a depending key portion formed integrallywith said plate-like formation and a pair of ears formed integrally withand between said plate formation and key portion, each said ear beingdisposed-in a leading direction relative to a'line 'transverse'to' said'key portion-and the directionofturnzingtofsaid drive shaft, saidcone-shaped body "of "said pilot "bit having a socket 'forrnedthereincomplementary to said key portion and said pair of ears forreceivingfthe same, and a pair of exit passages formed throughdhesidesof said cone-shaped body in communication with said socket thereinand exiting on-the rearmostjface of each of said helical blades of saidpilot bit, and said drive lug 'havingtan inlet port in register with thebore in said driveashaft and having two passages di-vergirrgthere- =fromfor'iexitto'the rearmost side of each ofsaid'ears whereby fluiddischarged from the bore of'sa-iddrive shaft is transmitted through saidsocket for exittherefrorn=viathe iex-it passages through saidhelicalblades, and 'ia'bo'lt extending through said pilot bit and *saidkey portion'for attaching'said pilot bit'to-said drive lug.

, References Cited in the file of this patent UNITED STATES PATENTS1,873,241 Wright Aug. 23, 193,2 2,365,941 Crake Dec. 26, "1944 2,569,275

Baker Sept. 25, 1-951

